Mass spectrometry is an analytical process that identifies the chemical composition of a compound or sample based on the mass-to-charge ratio of charged particles derived from the compound or sample. In general, in mass spectrometry, a sample undergoes ionization to form charged particles (ions). The ratio of mass-to-charge of the particles is determined by passing them through electric and/or magnetic fields in a mass spectrometer.
In some mass spectrometer systems, molecules can be analyzed in a quadrupole mass spectrometer using “electrospray” ionization to introduce the ions into the spectrometer. In electrospray ionization a spray needle may be positioned near to the entrance orifice of a quadrupole, magnetic, ion trap, Fourier transform mass spectrometer (FTMS), orbitrap, or time-of-flight (TOF) mass spectrometer, or close to the entrance of a capillary leading to a vacuum entrance orifice of the quadrupole or other type of mass spectrometer. A dilute solution, including the molecules of interest, is pumped through the electrospray needle or emitter and an electric potential between the needle or emitter orifice and a vacuum orifice (e.g., a reference electrode) leading to the mass analyzer forms a spray (“electrospray”) of the solution.